The zebrafish, Danio rerio, has become widely accepted as a model for human disease. Small molecule screens have been performed to identify both modifiers of normal cardiovascular processes and modifiers of cardiovascular disease. High-throughput systems under development aim to measure heart rate but do not address other critical parameters of cardiovascular function such as blood velocity, stroke volume and ejection fraction. We propose to develop a high-throughput system that would simultaneously: 1) measure heart rate;2) generate a velocity profile of the ventral aorta;and 3) measure end diastolic and end systolic ventricular volume. The microscope-based system will utilize spectral domain optical coherence tomography with Doppler to generate, within a matter of seconds, a three dimensional structural image of zebrafish embryos and larvae and measure blood flow. In Phase I we developed a breadboard system that enabled collection of images from both the dorsal and ventral views of the animals. In the breadboard system the animals were located and the scan angle was adjusted manually. In Phase II a complete, automated screening system will be developed that includes: 1) software algorithms to rapidly locate the animals for imaging and adjust the scan angle along their axial length;2) automated image collection;and 3) automated image processing. Phase II testing will include a pilot screen to detect animals with decreased cardiac output. PUBLIC HEALTH RELEVANCE: This research will develop technologies that will enable the use of zebrafish models of human disease in high-throughput screens for active pharmaceutical compounds. In particular, such screens are expected to accelerate discovery of new pharmaceuticals to treat cardiovascular diseases. These technologies will also enable high-throughput assays of cardiotoxicity.